3.1 GUIDELINES FOR INTEGRATION50 Installation Manual3.1 GUIDELINES FOR INTEGRATION3.1.1 DPT or Inband Signalling?There are 2 types of integration available on the VPS: Inband Signalling and DPT. The VPSused with any other brand of telephone equipment requires inband equipment.NoteDepending on the model and/or the software version of the connected PBX, you maynot be able to utilise some of the features available only with DPT Integration (see4.1.1 Why DPT Integration is Important). For more information, consult your dealer.3.1.2 Why Integration is ImportantThe VPS works well with most PBXs because its connections are made through a standardsingle-line (tip/ring) telephone interface. However, the VPS operation depends on thecapabilities and features provided by the PBX; its performance will vary when connected withdifferent PBX systems. For example, Follow-on (or Called Party) ID is a feature of the PBX. Ifthe PBX does not have this feature, the VPS cannot transfer calls directly to the correct mailboxand play the Busy or No Answer greeting for that mailbox.3.1.3 How the VPS and the PBX CommunicateTo the PBX, the VPS looks like an SLT. The PBX thinks that the VPS is an SLT, and the VPSmimics all actions a live attendant would carry out from an SLT.For the VPS and the PBX to communicate, proper signalling is important. Like an attendant,the VPS places calls by going off-hook and dialling numbers. It starts call transfers with a flash(recall) to put callers on hold and then dials the extension number. By recognising call progresstones from the PBX, the VPS decides how calls should be handled. Inband Integration allowsthe PBX to send certain digits (touchtone) to the VPS, allowing it to recognise the status of theextension and take the appropriate action.The VPS must also have access to certain PBX features. For example, if the VPS takes amessage, one way it can notify the mailbox owner is by dialling the PBX’s Message-Waiting-Lamp-On code. Once new messages are retrieved, the VPS dials the Message-Waiting-Lamp-Off code for that same mailbox owner.Table 3-1VPS/PBX COMMUNICATIONPBX to VPS VPS to PBXCall Progress Tones SLT Signals• ringback• busy• reorder• on/off hook• flash (recall)• touchtonesTouchtones
